Storage tanks for storing gasoline and other fuels at service stations are typically but not always buried in the ground. When buried, manholes having removable covers positioned at or adjacent ground level provide access to buried storage tanks as well as components connected to buried storage tanks. Manholes typically house fill pipes that are connected to the interior of the storage tanks. Storage tanks are typically serviced by tanker trucks which have hoses that connect to a fitting mounted on or about a fill pipe housed in the manhole.
The fuel level in buried storage tanks is typically monitored by the insertion of a measuring stick or graduated pole through the fill pipe into the storage tank to the bottom thereof. Upon withdrawal of the measuring stick, the wet area of the stick will indicate the level of fuel in the storage tank.
Overfilling of storage tanks with gasoline or similar fuels causes spillage of such fuels onto the ground which results in soil and air contamination and possibly other detrimental ecological consequences. It has been previously proposed to provide devices for preventing the flow of fuel into storage tanks when the storage tanks are filled to a preselected level of its maximum capacity. One such device is the overfill prevention valve disclosed in U.S. Pat. No. 5,518,024 the entire contents of which are incorporated herein by reference. However, for purposes of interpreting the meaning of the claims of the subject invention, the subject Specification without reference to U.S. Pat. No. 5,518,024 is to be used to ascertain the meaning of the claims.
In order to prevent tampering and/or damage from accidental impacts or the like, overfill prevention valves are preferably located entirely within the liquid storage tank.
Overfill prevention valves typically include a flow control member having a closure element which moves from an open position to a closed position to control flow of fuel into the liquid storage tanks. When in the closed position, the flow control member generally prevents fuel from escaping out an outlet of the overfill prevention valve, i.e., no significant amount of fuel escapes out the outlet. When in an open position, the flow control member allows fuel to flow through the outlet of the overfill prevention valve and enter the liquid storage tank through a portion of piping connected to the lower end of the overfill prevention valve.
Devices have previously been provided for testing the operability of the overfill prevention valve to verify that the overfill prevention valve will properly control the flow of fuel into the liquid storage container. However, these previously developed devices suffer from numerous deficiencies which will be readily apparent to one of ordinary skill in the art when a comparison is made between the subject invention and previously known devices.